12 



PERIPATUS 



largest part of the alimentary canal. It is a dilated soft-walled 

 tube, and leads behind into the short narrow rectum (H), which 

 opens at the anus. There are no glands opening into the 

 alimentary canal. 



Nervous System. 



The central nervous system consists of a pair of supra- 

 oesophageal ganglia united in the middle line, and of a pair of 

 widely divaricated ventral cords, continuous in front with the 

 Rupra-oesophageal ganglia (Fig. 9). 



Tlie ventral cords at first sight appear to be without gangli- 

 onic thickenings, but on more careful examination they are 

 found to be enlarged at each pair of legs (Fig. 9 ). These enlarge- 

 ments may he regarded as imperfect ganglia. There are, there- 



FlG. 9. — Brain and anterior part of the ventral nerve- 

 cords of Peripatiis capensis enlarged and viewed 

 from tLe ventral surface. (After Balfour.) The 

 paired appendages (cZ ) of the ventral surface of the 

 brain are seen, and the pair of syraj^athetic jierves 

 («?/) arising from the ventral surface of the hinder 

 part. From the commencement of the oesopha- 

 geal commissures pass off on each side a pair of 

 nerves to the jaws (/»). The three anterior 

 commissures between the ventral nerve-cords are 

 placed close together ; immediately behind them 

 the nerve-cords are swollen, to form the ganglionic 

 enlargements from which pass oif to the oral 

 papillae a pair of large nerves on each side (mii). 

 Behind this the cords present a series of enlarge- 

 ments, one pair for each pair of feet, from wliich a 

 pair of large nerves pass off on each side to the feet 

 {pn). atii, Antennary nerves ; co, commissures 

 between ventral cords ; d, ventral appendages of 

 brain ; E, eye ; en, nerves passing outwards from 

 ventral cord ; F.gA, ganglionic enlargements from 

 which nerves to feet pass off ; jn, nerves to jaws ; 

 orfi, ganglionic enlargement from which nerves to 

 oral papillae pass off ; orn, nerves to oral papillae ; 

 pc, posterior lobe of brain ; pn, nerves to feet ; 

 sij, .sympathetic nerves. 



fore, as many pairs of ganglia as there are pairs of legs. There 

 is in addition a ganglionic enlargement at the commencement of 

 the oesophageal commissures, where the nerves to the oral papillae 

 are given olf (Fig. 9, or.g). 



The ventral cords are placed each in the lateral compart- 

 ments of the body cavity, immediately within the longitudinal 

 layer of muscles. They are connected with each other, rather 

 like the pedal nerves of C%(7o» and the lower Prosobranchiata, 

 by a numljer of commissures. These commissures exhibit a 



